SummaryThis report describes the work performed by Pacific Northwest Laboratory (PNL) during the first quarter of FY 1995 (October -December 1994) under the Tank Waste Treatment Science Task of the Tank Waste Remediation System (TWRS) Pretreatment Technology Development Project. Work was performed in the following areas: 1) analytical methods development, 2) sludge dissolution modeling, 3) sludge characterization studies, 4) sludge component speciation, 5) pretreatment chemistry evaluation, and 6 ) colloidal studies for solid-liquid separations. Significant accomplishnients are highlighted below:Installation and testing of a particle size analysis system and a capillary'ion analyzer.Testing the existing thermodynamic model for the major electrolyte components of tank wastes by comparing predicted solubilities of NaNO, and NaNO, in simulated waste with direct exper-.imental observations. Submission of three papers for publication in the ACS Symposium Series on Scientific IssuesRelated to Safety and Treatment of Hanford Wastes. Presentation of a seminar entitled "Speciation of Sr and Ni in Tanks C-112 and C-109Sludges. " Fabrication (Los Alamos National Laboratory) of eight sample holders and two sample assemblies from a corrosion-resistant alloy for x-ray absorption spectroscopy experiments performed in March 1995 at the Stanford Synchrotron Radiation Laboratory.Development of the data structure for the statistical analysis of physical and rheological tank waste properties using the Sort on Radioactive Waste Type (SORWT) methodology.Obtaining and structuring the "Braun database" that contains records of historical analytical data for evaluation with the SORWT model to provide a tank-by-tank estimate of analyte concentrations.Preparation and characterization of colloidal suspensions of boehmite (AlOOH) and gibbsite [AI(OH),], in terms of primary particle size and shape, surface charge, and degree of agglomeration. While it is too early to draw definitive conclusions, the work performed to date suggests the following information about current guidelines.1. It appears that many of the current guidelines used in evaluating the baseline processes for solid-liquid separations are valid if the primary particles in sludge are larger than 10 pm in size. With large particles it is possible to achieve low slurry viscosities (< 60 cp) at high solids loadings (> 10 ~0 1 % ) for retrieval and transport, to have reasonable initial sedimentation velocities ( > 3 c d h r ) for settle-decant operations, and to achieve rapid filtration rates (> 1 cm/hr).iii 2 . The current processing guidelines do not appear to be valid if the bulk of the material to be processed consists of submicron particles. Fine colloidal particles can form highly viscous (> 25,000 cp) shear-thinning liquids at solids loadings as low as 3 vol%, can form suspensions that exhibit negligible sedimentation velocities (either in the form of highly dispersed suspensions or as highly agglomerated gels), and can form impermeable filter cakes that will clog most filtra...

SummaryThis report describes the work performed by the Pacific Northwest Laboratory during the second quarter of FY 1995 (January -March 1995) under the Tank Waste Treatment Science Task of the Tank Waste Remediation System Pretreatment Technology Development Project. Work was performed in the following areas: 1) analytical methods development, 2) sludge dissolution modeling, 3) sludge characterization studies, 4) sludge component speciation, 5) pretreatment chemistry evaluation, and 6) colloidal studies for solid-liquid separations. Significant accomplishments during the second quarter FY 1995 are highlighted below:The particle size analysis system for measuring of particulates in solution is ready for general research use, with user-verified operating procedures.Computer code modifications were completed, which allow the computation of parameters for the ESP model using our extensive thermodynamic properties database.A model for plutonium solubility in mixed NaOH/NaNO,/NaNO, systems was developed that provides predictions in good agreement with the experimental data.Transmission electron microscopy studies of Tank T-1 1 1 samples indicates that sludge washing removes the soluble phosphate salts [e.g., NqH(PO,),]; does not affect the other major components of iron, bismuth, manganese, and silicon, which appear to exist as amorphous FGBi(SiO,),OH; and causes the larger agglomerates to disperse into fine aggregates with a primary aggregate size of -50 nm, making solid-liquid separations difficult.X-ray diffraction analysis of Tank S-104 sludge indicates that the majority crystalline phase is boehmite. The colloidal properties of boehmite have been extensively studied in this task, and boehmite has been observed to form a variety of stable colloidal dispersions.Strontium incorporation into calcium minerals in several tank sludges was confirmed by x-ray absorption spectroscopy.Studies were initiated that were designed to develop sludge wash factors for single-shell tank wastes via analysis of experimental and historical tank inventory data.A preliminary statistical analysis using the SORWT model to evaluate tank waste physical properties indicated that centrifuged solids density is the only physical property with significant differences between SOWRT groups.Studies of Fe(OH), and Tank C-103 sludge simulant suspensions indicate that their colloidal properties are qualitatively the same as those of beohmite and gibbsite, and that baseline assumptions concerning solid-liquid separations may be inadequate.iii Results suggest the sensitivity of sedimentation rate to container geometry is due to an "instability" regime in the formation of floc networks, which must be accounted for in the design and interpretation of sedimentation experiments.Studies of Tank C-103 simulant suggest that apatite is capable of scavenging fine particles from basic supernatant liquids via a heterocoagulation process. iv

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The Sort on Radioactive Waste Type (SORWT) model presents a method to categorize Hanford Site single-shell tanks (SSTs) into groups of tanks expected to exhibit similar chemical and physical characteristics based on their major waste types and processing histories. This model has identified 29 different waste-type groups encompassing 135 of the 149 SSTs and 93 % of the total waste volume in SSTs. The remaining 14 SSTs and associated wastes could not be grouped according to the established criteria and were placed in an ungrouped category. This letter report will detail the assumptions and methodologies used to develop the SORWT model and present the grouping results. Included with this report is a brief description and approximate compositions of the single-shell tank waste types. In the near future, the validity of the predicted groups will be statistically tested using analysis of variance of characterization data obtained from recent (post-1989) core sampling and analysis activities. In addition, the SORWT model will be used to project the nominal waste characteristics of entire waste type groups that have some recent characterization data available. These subsequent activities will be documented along with these initial results in a comprehensive, formal PNL report cleared for public release by September 1994.

This document, prepared by the Pacific Northwest Laboratory (PNL) under the direction of Westinghouse Hanford Company (WHC), provides a detailed solid waste system description that documents the treatment, storage, and disposal (TSD) strategy for managing Hanford's solid low-level waste (LLW), low-level mixed waste (LLMW), transuranic and transuranic mixed (TRU-TRUM) waste, and greater-than-Class 111 (GTCIII) waste. This system description is intended for use by managers of the solid waste program, facility and system planners, as well as system modelers. The system description identifies the TSD facilities that constitute the solid waste system and defines these facilities' interfaces, schedules, and capacities. In addition, this system description provides the strategy for treating each of the waste streams generated or received by the Hanford Site from generation or receipt through final destination. Assumptions related to these waste process flows are also documented. Three storage facilities-two existing and one planned-will provide storage for Hanford's solid waste inventory and solid waste to be generated or shipped to the Hanford site. Storage will be required for batching waste into treatment facilities, for housing waste until treatment or disposal capacity is available, and for storing waste being transferred from one treatment facility to another. These facilities are: the (existing) Radioactive Mixed Waste Storage Facility, the (planned) Enhanced Radioactive Mixed Waste Storage Facility, and the (existing) Transuranic Storage and Assay Facility (TRUSAF). Four treatment facilities have been identified for processing waste volumes to meet disposal requirements. * Waste Receiving and Processing (WRAP) Module 1. The primary function of WRAP 1 will be to certify CH-TRU-TRUM waste in drums and standard waste boxes (SWBs) for shipment to the Waste Isolation Pilot Plant (WIPP). In addition, WRAP 1 will perform lot sampling on CH-LLW-I in drums prior to the lot's disposal in the LLW Burial Ground. This facility, which is currently under construction, is planned to begin processing CH-LLW-I in 1997 and CH_TRU_TRUM in 1998..-, The Commercial LLMW Stabilization Treatment Program (STP). The LLMW STP will process CH-LLh4W in drums and boxes smaller than 6 ft x 8 ft x 12 ft, to meet Resource Conservation and Recovery Act (RCRA) requirements for disposal in the mixed waste disposal trenches. The facility is expected to begin operation in 1999. Thermal Treatment Facility (TTF). The TTF will treat CH-LLMW in drums that contain physical waste forms or hazardous constituents requiring thermal destruction, such as organics and polychlorobiphenyls (PCBs). The treated LLMW will be shipped to the mixedswaste disposal trenches for disposal. The TTF is expected to begin operation in 1997.